Ventilation appliances of this type have long been part of the state of art as taught by German Pats. No. DT-PS 279 874 and No. DT-PS 319 203 . The relative motion of the baffle or stop plate against the front panel has been brought about by lever gears. Because of the use of these lever gears, the known ventilation appliances can be manufactured only with relatively short longitudinal dimensions, because only then can it be assured to some extent that they achieve an adequate sealing in the closed position of the stop plates. To be sure, in German Pat. No. DT-AS 1 249 489 the proposal has already been made to provide ventilation appliances having a considerable length relative to their width, i.e., so-called "slot" ventilators, with a baffle plate that is movable transversely of its plane and to the plane of the perforated or slotted front panel. In that case, the movement of the baffle plate is controlled by a steering knuckle arm disposed in the manner of a parallelogram, so that (for the purpose of transverse motion) there is also superimposed on the stop plate a longitudinal motion. The actual adjusting motion for the stop plate is derived from a crank assembly which is pivotally mounted at the front panel for movement about an axis that is oriented transversely of its plane, the crank pin having a length such that the stop plate can move along it during its transverse motion.
An essential disadvantage of all known ventilation appliances of this type lies in the fact that the mounting of the levers and handles having to do with the control mechanism can only be provided at the front panel and the stop plate at quite definite locations. This, however, not only limits the attainable sealing effect in closed position of the ventilation appliance, but also its structural length cannot be selected arbitrarily to correspond to various needs. It is, therefore, an outstanding object of the invention to provide air vent which eliminates the disadvantages characteristic of the known ventilation appliances of this type.
Another objection of this invention is the provision of air vent of this type of construction whose main component parts can be manufactured as standard elements that can be subdivided into random lengths, and wherein, after assembly, a uniformly-tight seal is assured at all parts of the baffle plate lying against the front panel.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.